Systems and methods for digital document processing

ABSTRACT

Systems that employs an adaptable front end for determining a file-type to associate with the output from a source application and for processing the output, as a function of the file type, to generate a display list that is representative of objects and shapes that represent components within the visual presentation of the data. The display list is then processed by a rendering engine, which may be located on an embedded device. The rendering engine processes the components contained within the display list to render an image of the source application&#39;s output that may be presented on the display of the device. As will be described below, the adaptable front end determines the file structure of the source being processed, thereby providing a device that may operate with a plurality of different file types, and source applications.

RELATED APPLICATIONS

This application claims priority to the earlier filed British PatentApplication No. 0009129.8, filed 14 Apr. 2000, and having Majid Anwar asan inventor, the contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to data processing systems. More particularly, theinvention relates to methods and systems for processing “digitaldocuments” (as defined herein) and to devices incorporating such methodsand systems. In general terms, the invention is concerned withgenerating an output representation of a source document; e.g., as avisual display or as hardcopy.

BACKGROUND

As used herein, the term “digital document” is used to describe adigital representation of any type of data processed by a dataprocessing system which is intended, ultimately, to be output in someform, in whole or in part, to a human user, typically by being displayedor reproduced visually (e.g., by means of a visual display unit orprinter), or by text-to-speech conversion, etc. A digital document mayinclude any features capable of representation, including but notlimited to the following: text; graphical images; animated graphicalimages; full motion video images; interactive icons, buttons, menus orhyperlinks. A digital document may also include non-visual elements suchas audio (sound) elements.

Data processing systems, such as personal computer systems, aretypically required to process “digital documents,” which may originatefrom any one of a number of local or remote sources and which may existin any one of a wide variety of data formats (“file formats”). In orderto generate an output version of the document, whether as a visualdisplay or printed copy, for example, it is necessary for the computersystem to interpret the original data file and to generate an outputcompatible with the relevant output device (e.g., monitor, or othervisual display device or printer). In general, this process will involvean application program adapted to interpret the data file, the operatingsystem of the computer, a software “driver” specific to the desiredoutput device and, in some cases (particularly for monitors or othervisual display units), additional hardware in the form of an expansioncard.

This conventional approach to the processing of digital documents inorder to generate an output is inefficient in terms of hardwareresources, software overheads and processing time, and is completelyunsuitable for low power, portable data processing systems, includingwireless telecommunication systems, or for low cost data processingsystems such as network terminals, etc. Other problems are encounteredin conventional digital document processing systems, including the needto configure multiple system components (including both hardware andsoftware components) to interact in the desired manner, andinconsistencies in the processing of identical source material bydifferent systems (e.g., differences in formatting, color reproduction,etc.). In addition, the conventional approach to digital documentprocessing is unable to exploit the commonality and/or re-usability offile format components.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide digital documentprocessing methods and systems, and devices incorporating such methodsand systems, which obviate or mitigate the aforesaid disadvantages ofconventional methods and systems.

More particularly, the systems and methods described herein includesystems that employs an adaptable front end for determining a file-typeto associate with the output from a source application and forprocessing the output, as a function of the file type, to generate adisplay list that is representative of objects and shapes that representcomponents within the visual presentation of the data. The display listis then processed by a rendering engine, which may be located on anembedded device. The rendering engine processes the components containedwithin the display list to render an image of the source application'soutput that may be presented on the display of the device. As will bedescribed below, the adaptable front end determines the file structureof the source being processed, thereby providing a device that mayoperate with a plurality of different file types, and sourceapplications.

Additionally, and optionally, the rendering engines described hereinwill provide for progressive rendering of images on the display of thedevice. This provides a visual display interface that will render imagesmore quickly by having the finer features within the presentation appearsubsequent to the more easily rendered features within the presentation.Additionally, as the system described herein may break a document downinto component objects, each of the objects may be processed separatelyincluding processing objects with special effects, such as shading,coloring, and transparency, thereby providing a layered look to imagespresented by the system described herein.

In a first aspect, the invention relates to a digital documentprocessing system comprising a mechanism for receiving an inputbytestream representing source data in one of a plurality ofpredetermined data formats; an interpreting mechanism for interpretingthe byteststream.

A converting device for converting interpreted content from thebytestream into an internal representation data format, and a device forprocessing the internal representation data so as to generate outputrepresentation data adapted to drive an output device.

In a second aspect, the invention relates to a graphical user interfacefor a data processing system in which interactive visual displaysemployed by the user interface are generated by means of a digitaldocument processing system in accordance with the first aspect of theinvention and to data processing systems incorporating such a graphicaluser interface.

In further aspects, the invention relates to various types of deviceincorporating a digital document processing system in accordance withthe first aspect of the invention, including hardware devices, dataprocessing systems and peripheral devices.

In still another aspect, the invention relates to a graphical userinterface for a data processing system, having one or more of a numberof novel and/or enhanced features, and to data processing systemsincorporating such a graphical user interface.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

The foregoing and other objects and advantages of the invention will beappreciated more fully from the following further description thereof,with reference to the accompanying drawings wherein;

FIG. 1 is a functional block diagram illustrating an embodiment of adigital document processing system in accordance with the presentinvention.

FIG. 2 is a functional block diagram that shows the system of theinvention in greater detail;

FIG. 3 is a data flow diagram depicting the operational flow of datathrough a system such as the system depicted in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The systems and methods described herein will now be described withreference to certain illustrative applications and embodiments,including embodiments that are well suited for identifying a file typeassociated with a source application's output, such as a documentproduced by a word processing application, to generate a representationof the visual display of that output, wherein the representation ispresented in an abstract form that may be rendered by a rendering engineadapted for a particular platform, such as a hand-held device. However,the systems and methods described herein may be employed in otherapplications and the embodiments depicted herein are merely illustrativeof certain embodiments of the invention, and are not to be understood aslimiting in any way.

Turning now to FIG. 1, one system 8 according to the invention isdepicted. Specifically, FIG. 1 depicts the system 8, a data processor 13having a plurality of executing processes, a plurality of output sourcestreams 10 and an output display 26. The data processor 13 can be anysuitable data processing platform including a conventional dataprocessing platform, such as a pc workstation or a server. The processesexecuting on the data processor may be any application that produces anoutput source that is to be, or may be, rendered on a display. Forexample, the depicted processes may include word processing programsthat generate .doc files, which may be presented a pages on a visualdisplay. Similarly, the processes 13 may include a web server thatdelivers HTML, XML, streaming multi-media, or PDF files for display by abrowser. The depicted output target device 26 may be any suitable devicethat can act as a display for the source being delivered by theprocesses 13.

Accordingly, FIG. 1 depicts that the system 8 of the invention cancouple to the output sources of a plurality of different applications,as well as output sources that differ in format. The system 8 canidentify the format of each source and process the source as a functionof its format. The processed source can be presented in a formatsuitable for presentation on the display of the target device 26.

FIG. 2 depicts in more detail the system 8 of FIG. 1. Specifically, FIG.2 depicts a plurality of application sources 10, the system 8 thatincludes an input module 11, or front end, a plurality of document agentprocesses 12, a display list 14 representative of an internalrepresentation of the visual image that is associated with theapplication source 10 being processed, a rendering module 18 and alibrary of generic objects 19.

The adaptive front end 11 includes a plurality of document agents 12.Each document agent 12 can be a software or hardware module that iscapable of receiving a stream, such as a Unix stream or Java stream,that is associated with an application source 10. The document agent 12can sort through the stream to determine whether the agent 12 recognizesthe format of that stream. If the format is recognized as belonging tothat agent 12, the agent 12 can begin processing fully the input stream.The processing of an output source can include parsing the source toidentify tokens within the source representative of the image that is tobe displayed. These tokens can include text, fonts, bit-maps and othersuch identifiers.

In the depicted embodiment, the front end 11 includes a plurality ofdifferent document agents, each being associated with a different formatoutput source. By providing a plurality of document agents 12 and byallowing each document agent 12 to examine the output source that is tobe processed, the system of FIG. 2 is a pluripotent processing enginethat can display the output source of multiple files.

As the document agent 12 processes the output stream, the agent 12builds a new data file, the display list 14, that encodes the visualimage presented by the output source. The display list 14 comprises aninternal representation of the visual image. The display list 14 can bepassed to the rendering engine 18, which will process the informationwithin the display list to create the visual image on the target outputdevice 26. To this end, the document agent 12 builds the internalrepresentation 14 of the visual image, by creating a file that includesa set of pointers to a library of known objects. When the renderingengine 18 operates, the library 19 of known objects is referenced andthe objects retrieved from the library 19 for display on the targetdisplay device.

Although FIGS. 1 and 2 graphically depict the system 8 as comprisingfunctional block elements, it will be apparent to one of ordinary skillin the art that these elements can be realized as computer programs orportions of computer programs that are capable of running on a dataprocessor platform, such as the target device 26, to thereby configurethe data processor as a system according to the invention. Theseprograms can be realized as software components operating on aconventional data processing system such as a Unix workstation, and canbe implemented as a C language computer program, or a computer programwritten in any high level language including C++, Fortran, Java orbasic. Additionally, in an embodiment where microcontrollers or DSPs areemployed, the systems described herein can be realized as a computerprogram written in microcode or written in a high level language andcompiled down to microcode that can be executed on the platformemployed.

Referring now to the drawings, a digital document processing system 8embodying the invention is illustrated in FIG. 3.

In general terms, the system 8 will process a source document 10comprising a data file in a known format. The input to the system 8 is abytestream comprising the content of the source document. An inputmodule 11 identifies the file format of the source document on the basisof any one of a variety of criteria, such as an explicit file-typeidentification within the document, from the file name (particularly thefile name extension), or from known characteristics of the content ofparticular file types. The bytestream is input to a “document agent” 12,specific to the file format of the source document. The document agent12 is adapted to interpret the incoming bytestream and to convert itinto a standard format employed by the system 8, resulting in aninternal representation 14 of the source data in a “native” formatsuitable for processing by the system 8. The system 8 will generallyinclude a plurality of different document agents 12, each adapted toprocess one of a corresponding plurality of predetermined file formats.

The system 8 may also be applied to input received from an input devicesuch as a digital camera or scanner. In this case the input bytestreammay originate directly from the input device, rather from a “sourcedocument” as such. However, the input bytestream will still be in apredictable data format suitable for processing by the system and, forthe purposes of the invention, input received from such an input devicemay be regarded as a “source document.”

The document agent 12 employs a library 16 of standard objects togenerate the internal representation 14, which describes the content ofthe source document in terms of a collection of generic objects asdefined in the library 16, together with parameters defining theproperties of specific instances of the various generic objects withinthe document. It will be understood that the internal representation maybe saved/stored in a file format native to the system and that the rangeof possible source documents 10 input to the system 8 may includedocuments in the system's native file format. It is also possible forthe internal representation 14 to be converted into any of a range ofother file formats if required, using suitable conversion agents (notshown).

The generic objects employed in the internal representation 14 willtypically include: text, bitmap graphics and vector graphics (which mayor may not be animated and which may be two- or three-dimensional:video, audio and a variety of types of interactive objects such asbuttons and icons. The parameters defining specific instances of genericobjects will generally include dimensional co-ordinates defining thephysical shape, size and location of the object and any relevanttemporal data for defining objects whose properties vary with time(allowing the system to deal with dynamic document structures and/ordisplay functions). For text objects, the parameters will normally alsoinclude a font and size to be applied to a character string. Objectparameters may also define other properties, such as transparency.

The format of the internal representation 14 separates the “structure”(or “layout”) of the documents, as described by the object types andtheir parameters, from the “content” of the various objects; e.g. thecharacter string (content) of a text object is separated from the font,character size and dimensional parameters of the object; the image data(content) of a graphic object is separated from its dimensionalparameters. This allows document structures to be defined in a verycompact manner and provides the option for content data to be storedremotely and to be fetched by the system only when needed.

The internal representation 14 describes the document and itsconstituent objects in terms of “high-level” descriptions.

The internal representation data 14 is input to a parsing and renderingmodule 18 which generates a context-specific representation 20 or “view”of the document represented by the internal representation 14. Therequired view may be of the whole document or of part(s) (subset(s))thereof. The parser/renderer 18 receives view control inputs 40 whichdefine the viewing context and any related temporal parameters of thespecific document view which is to be generated. For example, the systemmay be required to generate a zoomed view of part of a document, andthen to pan or scroll the zoomed view to display adjacent portions ofthe document. The view control inputs 40 are interpreted by theparser/renderer 18 in order to determine which parts of the internalrepresentation are required for a particular view and how, when and forhow long the view is to be displayed.

The context-specific representation/view 20 is again expressed in termsof object types and parameters, using the library 16.

The parser/rendered 18 may also perform additional pre-processingfunctions on the relevant parts of the internal representation 14 whengenerating the required view 20 of the source document 10. The viewrepresentation 20 is input to a shape processor module 22 for finalprocessing to generate a final output 24, in a format suitable foredriving an output device 26, such as a display device or printer.

The pre-processing functions of the parser/renderer 18 may include colorcorrection, resolution adjustment/enhancement and anti-aliasing.Resolution enhancement may comprise scaling functions which preserve thelegibility of the content of objects when displayed or reproduced by thetarget output device. Resolution adjustment may be context-sensitive;e.g. the display resolution of particular objects may be reduced whilethe displayed document view is being panned or scrolled and increasedwhen the document view is static.

There may be a feedback path 42 between the renderer/parser 18 and theinternal representation 14, e.g. for the purpose of triggering an updateof the content of the internal representation 14, such as in the casewhere the document 10 represented by the internal representationcomprises a multi-frame animation. The output representation 20 from theparser/renderer 18 expresses the document in terms of “primitive”objects. For each document object, the representation 20 preferablydefines the object at least in terms of a physical, rectangle boundarybox, the actual shape of the object bounded by the boundary box, thedata content of the object, and its transparency.

The shape processor 22 interprets the representation 20 and converts itinto an output frame format 24 appropriate to the target output device26; e.g. a dot-map for a printer, vector instruction set for a plotter,or bitmap for a display device. An output control input 44 to the shapeprocessor 22 to generate output 24 suitable for a particular outputdevice 26.

The shape processor 22 preferably processes the objects defined by theview representation 20 in terms of “shape” (i.e. the outline shape ofthe object), “fill” (the data content of the object) and “alpha” (thetransparency of the object), performs scaling and clipping appropriateto the required view and output device, and expresses the object I termsappropriate to the output device (typically in terms of pixels by scanconversion or the like, for most types of display device or printer).

The shape processor 22 preferably includes an edge buffer which definesthe shape of an object in terms of scan-converted pixels, and preferablyapplies anti-aliasing to the outline shape. Anti-aliasing is preferablyperformed in a manner determined by the characteristics of the outputdevice 26 (i.e. on the basis of the control input 44), by applying agrey-scale ramp across the object boundary. This approach enables memoryefficient shape-clipping and shape-intersection processes.

A look-up table may be employed to define multiple tone response curves,allowing non-linear rendering control (gamma correction).

The individual object processed by the shape processor 22 are combinedin the composite output frame 24. The quality of the final output canalso be controlled by the user via the output control input 44.

The shape processor 22 has a multi-stage pipeline architecture whichlends itself to parallel processing of multiple objects, or of multipledocuments, or of multiple subsets of one or more document, by usingmultiple instances of the shape processor pipeline. The pipelinearchitecture is also easily modified to include additional processingfunctions (e.g. filter functions) if required. Outputs from multipleshape processors 22 may generate multiple output frames 24 or may becombined in a single output frame 24.

The system architecture is modular in nature. This enables, for example,further document agents to be added as and when required, to deal withadditional source file formats. The modular architecture also allowsindividual modules such as the library 16, parser/renderer 18 or shapeprocessor 22 to be modified or upgraded without requiring changes toother modules.

The system architecture as a whole also lends itself to parallelism inwhole or in part for simultaneous processing of multiple input documents10 a, 10 b, etc. or subsets of documents, in one or more file formats,via one or more document agents 12, 12 a. The integrated, modular natureof the system allows multiple instances of system modules to be spawnedwithin a data processing system or device as and when required, limitedonly by available processing and memory resources.

The potential for flexible parallelism provided by the system as a wholeand the shape processor 22 in particular allows the display path for agiven device to be optimized for available bandwidth and memory. Displayupdates and animations may be improved, being quicker and requiring lessmemory. The object/parameter document model employed is deterministicand consistent. The system is fully scalable and allows multipleinstances of the system across multiple CPUs.

The system preferably employs a device-independent color model, suitablea luminance/chrominance model such as the CIE L*A*B* 1976 model. Thisreduces redundancy in graphic objects, improves data compressibility andimproves consistency of color output between different output devices.Device-dependent color correction can be applied on the basis of thedevice-dependent control input 44 to the shape processor 22.

FIG. 3 shows the system having an input end at which the sourcebytestream is received and an output end where the final output frame 24is output from the system. However, it will be understood that thesystem may include intermediate inputs and outputs at other intermediatestages, such as for fetching data content or for saving/converting datagenerated in the course of the process.

The system 8 may be incorporated into a variety of types of dataprocessing systems and devices, and into peripheral devices, in a numberof different ways. In a general purpose data processing system (the“host system”), the system of the present invention may be incorporatedalongside the operating system and applications of the host system ormay be incorporated fully or partially into the host operating system.

For example, the system of the present invention enables rapid displayof a variety of types of data files on portable data processing deviceswith LCD displays without requiring the use of browsers or applicationprograms. This class of data processing devices requires small size, lowpower processors for portability. Typically, this requires the use ofadvanced RISC-type core processors designed in to ASICs (applicationspecific integrated circuits), in order that the electronics package isas small and highly integrated as possible. This type of device also haslimited random access memory and typically has no non-volatile datastore (e.g. hard disk). Conventional operating system models, such asare employed in standard desktop computing systems (PCs), require highpowered central processors and large amounts of memory in order toprocess digital documents and generate useful output, and are entirelyunsuited for this type of data processing device. In particular,conventional systems do not provide for the processing of multiple fileformats in an integrated manner. By contrast, the present inventionutilizes common processes and pipelines for all file formats, therebyproviding a highly integrated document processing system which isextremely efficient in terms of power consumption and usage of systemresources.

The system of the present invention may be integrated at the BIOS levelof portable data processing devices to enable document processing andoutput with much lower overhead than conventional system models.Alternatively, the invention may be implemented at the lowest systemlevel just above the transport protocol stack. For example, the systemmay be incorporated into a network device (card) or system, to providein-line processing of network traffic (e.g. working at the packet levelin a TCP/IP system).

In a particular device, the system of the invention is configured tooperate with a predetermined set of data file formats and particularoutput devices; e.g. the visual display unit of the device and/or atleast one type of printer.

Examples of portable data processing devices which may employ thepresent system include “palmtop” computers, portable digital assistants(PDAs, including tablet-type PDAs in which the primary user interfacecomprises a graphical display with which the user interacts directly bymeans of a stylus device), internet-enabled mobile telephones and othercommunications devices, etc.

The system may also be incorporated into low cost data processingterminals such as enhanced telephones and “thin” network clientterminals (e.g. network terminals with limited local processing andstorage resources), and “set-top boxes” for use ininteractive/internet-enabled cable TV systems.

When integrated with the operating system of a data processing system,the system of the present invention may also form the basis of a novelgraphical user interface *(GUI) for the operating system (OS). Documentsprocessed and displayed by the system may include interactive featuressuch as menus, buttons, icons etc. which provide the user interface tothe underlying functions of the operating system. By extension, acomplete OS/GUI may be expressed, processed and displayed in terms ofsystem “documents”. The OS/GUI could comprise a single document withmultiple “chapters”.

GUI features of this type provide new or enhanced functionality and/orimprove the subjective quality of the user interface.

The system of the present invention may also be incorporated intoperipheral devices such as hardcopy devices (printers and plotters),display devices (such as digital projectors), networking devices, inputdevices (cameras, scanners, etc.) and also multi-function peripherals(MPPs).

When incorporated into a printer, the system enables the printer toreceive raw data files from the host data processing system and toreproduce the content of the original data file correctly, without theneed for particular applications or drivers provided by the host system.This avoids the need to configure a computer system to drive aparticular type of printer. The present system directly generates adot-mapped image of the source document suitable for output by theprinter (this is true whether the system is incorporated into theprinter itself or into the host system). Similar considerations apply toother hardcopy devices such as plotters.

When incorporated into a display device, such as a projector, the systemagain enables the device to display the content of the original datafile correctly without the use of applications or drivers on the hostsystem, and without the need for specific configuration of the hostsystem and/or display device. Peripheral devices of these types, whenequipped with the present system, may receive and output data files fromany source, via any type of data communications network.

From the foregoing, it will be understood that the system of the presentinvention may be “hard-wired”; e.g. implemented in ROM and/or integratedinto ASICs or other single-chip systems, or may be implemented asfirmware (programmable ROM such as flashable ePROM), or as software,being stored locally or remotely and being fetched and executed asrequired by a particular device.

Improvements and modifications may be incorporated without departingfrom the scope of the present invention and those skilled in the artwill know or be able to ascertain using no more than routineexperimentation, many equivalents to the embodiments and practicesdescribed herein. For example, the systems may be employed for the useof thumbnail images of documents for navigation purposes and forrecording user activities (history); e.g. when browsing network content.Additionally, the systems can allow for document interaction functionsand gesture-based commands using pointing devices and/or touch-screentechnology. This may include allowing document interaction by means ofgestures analogous to actions used with physical documents or books,such as dragging a pointer across a page in order to turn the page(“page-flipping”), dragging a pointer to curl back the corner of a pageto view underlying parts of succeeding pages (“page curl”); Allowingtool selection by dragging tools from toolbars and de-selection bydragging tools to predetermined parts of the display; Symbolic cursormovements to indicate particular OS commands, such as “tick”,“cross-out” and “circle” movements for “OK”, “delete” and “select”;editing commands based on conventional “proof-readers” notation. Furtherapplications for the systems and methods described herein includere-formatting document views by rotation or switching between landscapeand portrait formats.

Additionally, the systems and methods described herein provide forutilities and tools such as, floating virtual “magnifying glass” whichmagnifies the underlying document area, in which the magnified view isbased on the internal representation 14 of the source document ratherthan on a bitmap representation of the document and which may modifydocument parameters such as background and/or foreground colors; afloating virtual, translucent keyboard for text input using a pointingdevice/touch screen; a floating, virtual, translucent ruler which isre-scalable using any of a variety of user-selectable units. The systemsalso provide for alternative menu or “tabbed page” drag out/pull downfunctions and simulation of physical inertia/momentum applied to pagescrolling/panning functions (e.g. when a zoomed display of a page isdragged to scroll the display and released, the moving displaydecelerates gradually after release).

Accordingly, it will be understood that the invention is not to belimited to the embodiments disclosed herein, but is to be understoodfrom the following claims, which are to be interpreted as broadly asallowed under the law.

1. An integrated digital document processing system comprising: anadaptable front end for receiving an input stream generated by anexternal application representing source data in one of a plurality ofpredetermined data formats and containing information representative ofa visual image, wherein the source data defines a content and astructure of a digital document; a library of generic objects; aninterpreting module for generating an internal representation of saidvisual image by i) identifying a plurality of structure instancesrepresentative of specific instances of the generic objects within thedigital document, ii) storing an identified structure instance as aninstance of a generic object selected from the library and havingparameters specific to the identified structure instance; iii)identifying content associated with the identified structure instance;and iv) storing the identified content apart from the stored genericobject instance corresponding to the structure instance; and a renderingengine integrated into the document processing system for processingsaid internal representation and for generating an output data streamsuitable for driving an output device to present the visual imageindependent of any application external to the integrated digitaldocument processing system.
 2. A system according to claim 1, whereinsaid adaptable front end includes a process for monitoring a data streamand for identifying files in any of the formats from the set consistingof HTML, XML, PDF, DOC, RM, VRML and SGML.
 3. A system according toclaim 1, further including a shape processing module adapted to receivean object and parameter based representation of the visual image and toconvert said object and parameter based representation into an outputdata format suitable for driving a particular output device.
 4. A systemaccording to claim 3, wherein said shape processing module processessaid objects on the basis of a boundary box defining the boundary of anobject, a shape defining the actual shape of the object bounded by theboundary box, the data content of the object and the transparency of theobject.
 5. A system according to claim 3 wherein said shape processor isadapted to apply grey-scale anti-aliasing to the edges of said objects.6. A system according to claim 3 wherein said shape processing modulehas a pipeline architecture.
 7. A system according to claim 1, whereinsaid internal representation includes object parameters havingdimensional, physical and temporal parameters.
 8. A system according toclaim 1, further including a chrominance/luminance-based color model todescribe color data.
 9. A system according to claim 1, wherein theoutput device is a display.
 10. A system according to claim 1, whereinthe output device is a monitor.
 11. A system according to claim 1,wherein the output device is a screen.
 12. A system according to claim1, wherein the output device is a printer.
 13. A system according toclaim 1 wherein the output device is a plotter.
 14. A system accordingto claim 1 wherein the output data stream is a bitmap.
 15. A systemaccording to claim 1 wherein the output data stream is a dot map for aprinter.
 16. A system according to claim 1 wherein the output datastream is a vector instruction set.
 17. A system according to claim 1,wherein said digital document includes at least one interactive feature,said internal representation includes graphical user interface objectsfor generating interactive visual displays, and the output data streamgenerated by the rendering engine is suitable to drive an output deviceto present an interactive visual image having the interactive feature ofsaid digital document.
 18. A system according to claim 17 wherein theinteractive feature is a menu.
 19. A system according to claim 17wherein the interactive feature is a button.
 20. A system according toclaim 17 wherein the interactive feature is an icon.
 21. A systemaccording to claim 1, wherein said rendering engine is configured toreceive a view control input for manipulating the presentation of thevisual image independent of the source data format of digital document.22. A system according to claim 21 wherein the view control input is azoom instruction.
 23. A system according to claim 21 wherein the viewcontrol input is a pan instruction.
 24. A system according to claim 21wherein the view control input is a scroll instruction.
 25. A systemaccording to claim 21 wherein the view control input defines the viewingcontext and related temporal parameters.
 26. A system according to claim25 wherein the viewing context is a magnification level.
 27. A systemaccording to claim 25 wherein the temporal parameters include a panspeed.
 28. A system according to claim 25 wherein the temporalparameters include a scroll speed.
 29. A system according to claim 25wherein the temporal parameters include a display duration.
 30. Anintegrated digital document processing system comprising: an adaptablefront end for receiving an input stream generated by an externalapplication representing source data in one of a plurality ofpredetermined data formats and containing information representative ofa visual image, wherein the source data defines a content and astructure of a digital document; an interpreting module for generatingan internal representation of said visual image by i) identifying a textobject having a content including a string of characters and parametersincluding at least the location of the text object within the digitaldocument and the font to be applied to the content; ii)storing aninstance of a generic text object along with the parameters of theidentified text object; iii) storing the string of characters in a dataobject other than the stored instance of the generic text object; and arendering engine integrated into the document processing system forprocessing said internal representation and for generating an outputdata stream suitable for driving an output device to present the textobject independent of any application external to the integrated digitaldocument processing system.
 31. An integrated digital documentprocessing system comprising: an adaptable front end for receiving aninput stream generated by an external application representing sourcedata in one of a plurality of predetermined data formats and containinginformation representative of a visual image, wherein the source datadefines a content and a structure of a digital document; an interpretingmodule for generating an internal representation of said visual image byi) identifying a graphic object having a content including a bitmapimage and parameters including at least the location of the graphicobject within the digital document and the display size of the image;ii)storing an instance of a generic graphic object along with theparameters of the identified graphic object; iii) storing the bitmapimage in a data object other than the stored instance of the genericgraphic object; and a rendering engine integrated into the documentprocessing system for processing said internal representation and forgenerating an output data stream suitable for driving an output deviceto present the graphic object independent of any application external tothe integrated digital document processing system.
 32. An integrateddigital document processing system comprising: an adaptable front endfor receiving an input stream generated by an external applicationrepresenting source data in one of a plurality of predetermined dataformats and containing information representative of a visual image,wherein the source data defines a content and a structure of a digitaldocument; an interpreting module for generating an internalrepresentation of said visual image by i) identifying a graphic objecthaving a content including a bitmap image and parameters including atleast the location of the graphic object within the digital document andthe display size of the image; ii)storing an instance of a genericgraphic object along with the parameters of the identified graphicobject; iii) storing the bitmap image in a data object other than thestored instance of the generic graphic object, iv) identifying a textobject having a content including a string of characters and parametersincluding at least the location of the text object within the digitaldocument and the font to be applied to the content; v)storing aninstance of a generic text object along with the parameters of theidentified text object; vi) storing the string of characters in a dataobject other than the stored instance of the generic text object; and arendering engine integrated into the document processing system forprocessing said internal representation and for generating an outputdata stream suitable for driving an output device to present the visualimage independent of any application external to the integrated digitaldocument processing system.